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refactor encoder and decoder functions
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@Aftersol
Aftersol committed Jul 30, 2023
1 parent 50d8b89 commit 82d890d
Showing 1 changed file with 89 additions and 43 deletions.
132 changes: 89 additions & 43 deletions inc/sQOI.h
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Original file line number Diff line number Diff line change
Expand Up @@ -78,6 +78,9 @@ enum qoi_pixel_color {QOI_RED, QOI_GREEN, QOI_BLUE, QOI_ALPHA};
enum qoi_channels {QOI_WHITESPACE = 3, QOI_TRANSPARENT = 4};
enum qoi_colorspace {QOI_SRGB, QOI_LINEAR};

/* QOI magic number */
static const uint8_t QOI_MAGIC[4] = {'q', 'o', 'i', 'f'};

/* QOI end of file */
static const uint8_t QOI_PADDING[8] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01};

Expand Down Expand Up @@ -175,18 +178,22 @@ bool read_qoi_header(qoi_desc_t *desc, void* data);

bool qoi_enc_init(qoi_desc_t* desc, qoi_enc_t* enc, void* data);
bool qoi_enc_done(qoi_enc_t* enc);

void qoi_encode_chunk(qoi_desc_t *desc, qoi_enc_t *enc, void *qoi_pixel_bytes);

static inline void qoi_enc_rgb(qoi_enc_t *enc, qoi_pixel_t px);
static inline void qoi_enc_rgba(qoi_enc_t *enc, qoi_pixel_t px);

static inline void qoi_enc_index(qoi_enc_t *enc, uint8_t index_pos);
static inline void qoi_enc_diff(qoi_enc_t *enc, uint8_t red_diff, uint8_t green_diff, uint8_t blue_diff);
static inline void qoi_enc_luma(qoi_enc_t *enc, uint8_t green_diff, uint8_t dr_dg, uint8_t db_dg);
static inline void qoi_enc_run(qoi_enc_t *enc);

/* QOI decoder functions */

bool qoi_dec_init(qoi_desc_t* desc, qoi_dec_t* dec, void* data, size_t len);
bool qoi_dec_done(qoi_dec_t* dec);

qoi_pixel_t qoi_decode_chunk(qoi_dec_t* dec);

static inline void qoi_dec_rgb(qoi_dec_t* dec);
Expand Down Expand Up @@ -307,10 +314,10 @@ void write_qoi_header(qoi_desc_t *desc, void* dest)
uint8_t *byte = (uint8_t*)dest;

/* Write the magic characters to the file first */
byte[0] = 'q';
byte[1] = 'o';
byte[2] = 'i';
byte[3] = 'f';
byte[0] = QOI_MAGIC[0];
byte[1] = QOI_MAGIC[1];
byte[2] = QOI_MAGIC[2];
byte[3] = QOI_MAGIC[3];

/* Writes all the metadata information about the image to the file */

Expand All @@ -332,10 +339,10 @@ bool read_qoi_header(qoi_desc_t *desc, void* data)
uint8_t *byte = (uint8_t*)data;

/* Check magic values for vaild QOIF file */
if (!(byte[0] == 'q' &&
byte[1] == 'o' &&
byte[2] == 'i' &&
byte[3] == 'f')
if (!(byte[0] == QOI_MAGIC[0] &&
byte[1] == QOI_MAGIC[1] &&
byte[2] == QOI_MAGIC[2] &&
byte[3] == QOI_MAGIC[3])
) return false;

/* Read the header for information on how big should the image be and how to decode the image */
Expand Down Expand Up @@ -418,6 +425,7 @@ bool qoi_dec_done(qoi_dec_t* dec)
return (dec->offset - dec->data > dec->qoi_len - 8) || (dec->pixel_seek >= dec->img_area); /* Has the decoder decoded all the pixels yet or reached the end of the file? */
}

/* Place the RGB information into the QOI file */
static inline void qoi_enc_rgb(qoi_enc_t *enc, qoi_pixel_t px)
{
uint8_t tag[4] = {
Expand All @@ -427,14 +435,15 @@ static inline void qoi_enc_rgb(qoi_enc_t *enc, qoi_pixel_t px)
px.blue
};

enc->offset[0] = tag[0];
enc->offset[1] = tag[1];
enc->offset[2] = tag[2];
enc->offset[3] = tag[3];
enc->offset[0] = tag[0]; /* RGB opcode */
enc->offset[1] = tag[1]; /* Red */
enc->offset[2] = tag[2]; /* Green */
enc->offset[3] = tag[3]; /* Blue */

enc->offset += 4;
}

/* Place the RGBA information into the QOI file */
static inline void qoi_enc_rgba(qoi_enc_t *enc, qoi_pixel_t px)
{
uint8_t tag[5] =
Expand All @@ -446,21 +455,52 @@ static inline void qoi_enc_rgba(qoi_enc_t *enc, qoi_pixel_t px)
px.alpha
};

enc->offset[0] = tag[0];
enc->offset[1] = tag[1];
enc->offset[2] = tag[2];
enc->offset[3] = tag[3];
enc->offset[4] = tag[4];
enc->offset[0] = tag[0]; /* RGBA opcode */
enc->offset[1] = tag[1]; /* Red */
enc->offset[2] = tag[2]; /* Green */
enc->offset[3] = tag[3]; /* Blue */
enc->offset[4] = tag[4]; /* Alpha */

enc->offset += 5;
}

/* Place the index position of the buffer into the QOI file */
static inline void qoi_enc_index(qoi_enc_t *enc, uint8_t index_pos)
{
/* The run-length is stored with a bias of -1 */
uint8_t tag = QOI_OP_INDEX | index_pos;
enc->offset++[0] = tag;
}

/* Place the differences between color values into the QOI file */
static inline void qoi_enc_diff(qoi_enc_t *enc, uint8_t red_diff, uint8_t green_diff, uint8_t blue_diff)
{
uint8_t tag =
QOI_OP_DIFF |
(uint8_t)(red_diff + 2) << 4 |
(uint8_t)(green_diff + 2) << 2 |
(uint8_t)(blue_diff + 2);

enc->offset[0] = tag;

enc->offset++;
}

/* Place the luma values into the QOI file */
static inline void qoi_enc_luma(qoi_enc_t *enc, uint8_t green_diff, uint8_t dr_dg, uint8_t db_dg)
{
uint8_t tag[2] = {
QOI_OP_LUMA | (uint8_t)(green_diff + 32),
(uint8_t)(dr_dg + 8) << 4 | (uint8_t)(db_dg + 8)
};

enc->offset[0] = tag[0];
enc->offset[1] = tag[1];

enc->offset += 2;
}

/* Place the run length of a pixel color information into the QOI file */
static inline void qoi_enc_run(qoi_enc_t *enc)
{
/* The run-length is stored with a bias of -1 */
Expand Down Expand Up @@ -513,7 +553,6 @@ void qoi_encode_chunk(qoi_desc_t *desc, qoi_enc_t *enc, void *qoi_pixel_bytes)
/* Write opcode for because there are differences in pixels
The run-length is stored with a bias of -1 */
qoi_enc_run(enc);

}

/* Check if pixels exist in one of the pixel hash buffers */
Expand All @@ -533,44 +572,32 @@ void qoi_encode_chunk(qoi_desc_t *desc, qoi_enc_t *enc, void *qoi_pixel_bytes)
else
{
/* Check the difference between color values to determine opcode */
int8_t red_dif, green_dif, blue_dif;
int8_t red_diff, green_diff, blue_diff;
int8_t dr_dg, db_dg;

red_dif = cur_pixel.red - enc->prev_pixel.red;
green_dif = cur_pixel.green - enc->prev_pixel.green;
blue_dif = cur_pixel.blue - enc->prev_pixel.blue;
red_diff = cur_pixel.red - enc->prev_pixel.red;
green_diff = cur_pixel.green - enc->prev_pixel.green;
blue_diff = cur_pixel.blue - enc->prev_pixel.blue;

dr_dg = red_dif - green_dif;
db_dg = blue_dif - green_dif;
dr_dg = red_diff - green_diff;
db_dg = blue_diff - green_diff;

if (
red_dif >= -2 && red_dif <= 1 &&
green_dif >= -2 && green_dif <= 1 &&
blue_dif >= -2 && blue_dif <= 1
red_diff >= -2 && red_diff <= 1 &&
green_diff >= -2 && green_diff <= 1 &&
blue_diff >= -2 && blue_diff <= 1
)
{
uint8_t tag =
QOI_OP_DIFF |
(uint8_t)(red_dif + 2) << 4 |
(uint8_t)(green_dif + 2) << 2 |
(uint8_t)(blue_dif + 2);
enc->offset[0] = tag;
enc->offset++;
qoi_enc_diff(enc, red_diff, green_diff, blue_diff);
}

else if (
dr_dg >= -8 && dr_dg <= 7 &&
green_dif >= -32 && green_dif <= 31 &&
green_diff >= -32 && green_diff <= 31 &&
db_dg >= -8 && db_dg <= 7
)
{
uint8_t tag[2] = {
QOI_OP_LUMA | (uint8_t)(green_dif + 32),
(uint8_t)(dr_dg + 8) << 4 | (uint8_t)(db_dg + 8)
};
enc->offset[0] = tag[0];
enc->offset[1] = tag[1];
enc->offset += 2;
qoi_enc_luma(enc, green_diff, dr_dg, db_dg);
}

/* otherwise write an RGB tag containting the RGB values of a pixel */
Expand Down Expand Up @@ -598,59 +625,78 @@ void qoi_encode_chunk(qoi_desc_t *desc, qoi_enc_t *enc, void *qoi_pixel_bytes)
enc->offset[5] = QOI_PADDING[5];
enc->offset[6] = QOI_PADDING[6];
enc->offset[7] = QOI_PADDING[7];

enc->offset += 8;
}
}

/* Get and set the RGB values from the QOI file */
static inline void qoi_dec_rgb(qoi_dec_t* dec)
{
dec->prev_pixel.red = dec->offset[1];
dec->prev_pixel.green = dec->offset[2];
dec->prev_pixel.blue = dec->offset[3];

dec->offset += 4;
}

/* Get and set the RGB values from the QOI file */
static inline void qoi_dec_rgba(qoi_dec_t* dec)
{
dec->prev_pixel.red = dec->offset[1];
dec->prev_pixel.green = dec->offset[2];
dec->prev_pixel.blue = dec->offset[3];
dec->prev_pixel.alpha = dec->offset[4];

dec->offset += 5;
}

/* Get and set the seek position of the buffer from the QOI file */
static inline void qoi_dec_index(qoi_dec_t* dec, uint8_t tag)
{
dec->prev_pixel = dec->buffer[tag & QOI_TAG_MASK];

dec->offset += 1;
}

/* Get the differences between values of the color channels from the QOI file */
static inline void qoi_dec_diff(qoi_dec_t* dec, uint8_t tag)
{
uint8_t diff = tag & QOI_TAG_MASK;

/* Do some wizardary to get the differences between three color channel values */

uint8_t red_diff = ((diff >> 4) & 0x03) - 2;
uint8_t green_diff = ((diff >> 2) & 0x03) - 2;
uint8_t blue_diff = (diff & 0x03) - 2;

/* Add up the differences between three color channel values individually */

dec->prev_pixel.red += red_diff;
dec->prev_pixel.green += green_diff;
dec->prev_pixel.blue += blue_diff;

dec->offset += 1;
}

/* Gets the luma values from the QOI file */
static inline void qoi_dec_luma(qoi_dec_t* dec, uint8_t tag)
{
uint8_t lumaGreen = (tag & QOI_TAG_MASK) - 32;

/* Do some lumaGreen wizardary to get and add the differences between three color channel values */

dec->prev_pixel.red += lumaGreen + ((dec->offset[1] & 0xF0) >> 4) - 8;
dec->prev_pixel.green += lumaGreen;
dec->prev_pixel.blue += lumaGreen + (dec->offset[1] & 0x0F) - 8;

dec->offset += 2;
}

/* Gets the run length of the pixel from the QOI file */
static inline void qoi_dec_run(qoi_dec_t* dec, uint8_t tag){
dec->run = tag & QOI_TAG_MASK;

dec->offset += 1;
}

Expand Down Expand Up @@ -736,4 +782,4 @@ qoi_pixel_t qoi_decode_chunk(qoi_dec_t* dec)

#endif /* SIMPLIFIED_QOI_IMPLEMENTATION */

#endif /* SIMPLIFIED_QOI_H_IMPLEMENTATION */
#endif /* SIMPLIFIED_QOI_H_IMPLEMENTATION */

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